The present disclosure relates to electronic circuits and methods, and in particular, to programmable stabilization circuits and methods.
The proliferation of wireless technologies and standards is placing ever increasing demands on electronic circuit technology. Circuits must be able to operate under drastically different operating conditions, and in some cases, must be able to perform well when a wireless system changes between various modes of operation. The complexities of this dynamic environment are particularly challenging for analog amplifiers, such as a power amplifier, in a wireless transmitter. A power amplifier, for example, may drive an antenna with enough output power to broadcast signals to a receiving system. Accordingly, the power amplifier must maintain stability when the wireless transmitter changes operating conditions during transmission, for example.
FIG. 1 illustrates a typical transistor device 110 used in a power amplifier circuit 100. One challenge with robust amplifier design pertains to the structure and parasitic effects of the transistors used to amplify signals in the transmission path. For example, some MOS transistor devices may have a very short gate length to compensate for high gate to drain capacitance (Cgd) 120 associated with some device structures. However, reducing the gate length can also cause the amplifier to become unstable under certain conditions. As illustrated by this example, some transistor devices and circuits designed to be stable for some operating conditions may be unstable for other operating conditions. However, conservative designs that are stable under all operation conditions may be highly inefficient in some situations, resulting in wasted power, for example.